The field of this invention is miter saws. In a compound miter saw, the miter angle and bevel angle of the saw blade can be adjusted independent of one another, or simultaneously to make compound angle cuts. Rotating the saw blade about a vertical miter axis adjusts the miter angle. The complement of the included angle that the saw blade makes with the miter saw's fence customarily represents the miter angle. Typically, a turntable is rotatably mounted on the miter saw's base to permit the miter angle adjustment.
Rotating the saw blade about a horizontal beveling axis adjusts the bevel angle. The beveling axis preferably lies in approximately the same plane as the top of the miter saw's base. The complement of the included angle that the saw blade makes with the top of the miter saw's base customarily represents the bevel angle. Many different arrangements have been devised for rotatably mounting a saw unit to the miter saw's base to permit adjustment of the bevel angle.
The saw unit which drives the saw blade also pivots about another horizontal axis which is perpendicular to the beveling axis to plunge the saw blade into a workpiece on the miter saw's base. Additional adjustments to the position of the saw unit relative to the base are also possible. These include sliding miter saws which permit the saw unit to translate horizontally along a plane parallel with the base's top surface while cutting.
This invention is concerned with improvements to miter saws which permit a bevel angle adjustment, thus including all compound miter saws. Miter saws which permit a bevel angle adjustment require a system for locking the saw unit at a desired bevel angle. The bevel angle must be locked to hold the desired bevel angle while making a cut. Also, often the same bevel angle is needed to make several cuts and locking the bevel angle ensures repeatability.
The system for locking the bevel angle is typically actuated by reaching around to the back of the miter saw and, for example, turning a locking handle. Reaching around to the back of the miter saw can be awkward, especially on large miter saws. Beveling the miter saw from −45° to +45° might require the user to reach around with his right hand to unlock the bevel angle locking system, use his left hand to rotate the saw unit from the −45° bevel angle to the 0° bevel angle, switch the saw unit to his right hand, use his right hand to rotate the saw unit from the 0° bevel angle to the +45° bevel angle, then use his left hand to reach around the miter saw to lock the bevel angle locking system. As can be seen, having to reach around the miter saw to actuate the bevel angle locking system is an inefficient and awkward arrangement. Some tasks performed with a miter saw, for example cutting crown molding, require the user to frequently change the miter saw's bevel angle from a negative to a positive bevel angle and back again. During such tasks, the difficulty in reaching around the back of the miter saw to lock the bevel angle locking system is particularly acute.
Saws which permit a bevel angle adjustment sometimes include a system for assisting the user in beveling the saw unit to certain commonly used bevel angles. For example, users commonly make cuts with bevel angles of 0°, ±45° and ±33.86°. These bevel angle adjustment assistance systems typically operate by assisting the user to tactilely recognize when the saw blade has reached a preset bevel angle, and may also assist the user in holding the saw unit at the preset bevel angle until the bevel angle can be locked. Some bevel angle adjustment assistance systems may include an override feature for overriding the assistance provided by the system. Depending upon the characteristics of the bevel angle adjustment assistance system, overriding might be necessary to bevel the saw unit beyond certain preset bevel angles.
The actuator for overriding the bevel angle adjustment assistance system is typically actuated by reaching around to the back of the miter saw and, for example, pressing a button or pulling or pushing on a rod or lever, etc. This can be awkward, especially if the miter saw is relatively large or the actuator is not placed in an easy to reach location.
The bevel angle adjustment assistance system might allow for fine tuning the preset bevel angles so that they precisely correspond to their respective intended bevel angles. These bevel angle adjustment assistance systems have required each preset bevel angle to be separately fine tuned to the intended bevel angle. If the manufacturer is to initially fine tune each of the preset bevel angles as part of the manufacturing assembly process, the multiple separate adjustments which are required can be laborious and as a result quite expensive for the manufacturer. This cost can be especially significant when there are three or more preset bevel angles. Also, the preset bevel angles may, on a relatively infrequent basis, need to be fine tuned by the user. The required multiple separate adjustments for fine tuning the preset bevel angles can be burdensome for the user, too.